Julesmusician From , joined Dec 1969, posts, RR: Posted (10 years 3 weeks 4 days 9 hours ago) and read 5569 times:
Following the incident over London where a 747 was running with very little engine power there have been recommendations that all pilots should be aware of their no power gliding profile of their aircraft - is this every done in simulators or if this did happen is it always down to a pilot's skill?
Fr8Mech From United States of America, joined Sep 2005, 6490 posts, RR: 16
Reply 4, posted (10 years 3 weeks 4 days 6 hours ago) and read 5516 times:
The EPR will less than 1.00 on descent.
The PT2 probe is located on the outboard side of the pylon. Left side for #1 & #2, right side for #3 & #4.
I've worked on the classics quite a bit, I believe I even worked N481EV, back in the day, and I've never heard of the '#6 throttle position'. He may have been referring to the index markings on the pedestal which are used by maintenance to mark throttle positions. 6 would have the throttle standing straight up, but nowhere near their max travel of about 11 or 12 (as I recall).
Interesting, according to the FDR graphic, the engines were stuck around the 1.15 - 1.21 range. This the 'bleed-shift' range (on the ground). As I recall, a JT9-7(x) that won't make power, but still has an increasing EGT, has not had 'bleed-shift'.
Bleed-shift is controlled on the engine independently of the other engines, except that one of th bleed controllers looks at air/ground logic. I just don;t remeber enough about chapter 75 on the JT9 to work it through my head any further.
PhilSquares From , joined Dec 1969, posts, RR:
Reply 5, posted (10 years 3 weeks 4 days 4 hours ago) and read 5457 times:
The number 6 position is just the thrust lever markings on the throttle quadrant. They're used for rigging.
As a technique, I avoid using V/S because you can get slow very easy. In the older JT-9 engines, if you got slow it really took a good airflow through the fan to make sure the engine would accelerate. As Fr8Mech pointed out, there is a bleed shift issue and the older engines really suffer from those problems.
KJFK31L From United States of America, joined Jan 2006, 148 posts, RR: 0
Reply 6, posted (10 years 3 weeks 4 days 2 hours ago) and read 5392 times:
The report cited that the aircraft engines have a bleed air issue when the 747 is operating "light". It also indicates that the way to rectify such an issue is to power up the engine (to position 6). After 10 seconds the valve will reset itself and normal flight can be resumed.
Is this a common problem for 747-200 cargo aircraft operating with small cargo loads?